Transmission method, reception method, transmitting device, and receiving device

ABSTRACT

A transmission method in the present disclosure includes; obtaining an image and image signal characteristics information indicating one of an opto-electrical transfer function (OETF) or an electro-optical transfer function (EOTF) as image signal characteristics of the image; and transmitting a signal including the image and the image signal characteristics information. According to the transmission method in the present disclosure, a receiving device that received a high dynamic range (HDR) image and a standard dynamic range (SDR) image transmitted through broadcasting or the like can display these images appropriately.

BACKGROUND 1. Technical Field

The present disclosure relates to a transmission method for transmittingan image or a reception method for receiving the image.

2. Description of the Related Art

In recent years, widening the dynamic range of luminance of video fromthe standard dynamic range (SDR) to the high dynamic range (HDR) hasbeen considered (for example, see non-patent literature (NPL) 1: WhitePaper Blu-ray (registered trademark) Disc Read-Only Format (Ultra HDBlu-ray) Audio Visual Application Format Specifications for BD-ROMVersion 3.0 July 2015, Blu-ray Disc Association). A broadcast stationnot only transmits video through normal broadcasting (basicbroadcasting), but also transmits text, graphics, etc., through databroadcasting.

SUMMARY

When an HDR image and an SDR image in NPL 1 are transmitted throughbroadcasting or the like, however, a receiving device is not capable ofdisplaying these images appropriately.

Thus, a non-limiting and exemplary embodiment disclosed herein providesa transmission method and the like that make it possible for a receivingdevice that received an HDR image and an SDR image transmitted throughbroadcasting or the like to display these images appropriately.

The transmission method according to one aspect of the presentdisclosure includes: obtaining an image and image signal characteristicsinformation indicating one of an opto-electrical transfer function(OETF) or an electro-optical transfer function (EOTF) as image signalcharacteristics of the image; and transmitting a signal including theimage and the image signal characteristics information.

Note that these general and specific aspects may be implemented using asystem, a method, an integrated circuit, a computer program, or acomputer-readable recording medium such as a compact disc read-onlymemory (CD-ROM), or any combination of systems, methods, integratedcircuits, computer programs, or recording media.

Additional benefits and advantages of the disclosed embodiment will beapparent from the specification and drawings. The benefits andadvantages may be individually obtained by the various embodiments andfeatures of the specification and drawings, which need not all beprovided in order to obtain one or more of such benefits and advantages.

According to the transmission method in the present disclosure, thereceiving device that received the HDR image and the SDR imagetransmitted through broadcasting or the like can display these imagesappropriately.

BRIEF DESCRIPTION OF DRAWINGS

These and other objects, advantages and features of the disclosure willbecome apparent from the following description thereof taken inconjunction with the accompanying drawings that illustrate a specificembodiment of the present disclosure.

FIG. 1 illustrates one example of the configuration of a transmittingand receiving system and one example of the screen displayed on areceiving device according to an embodiment;

FIG. 2 illustrates an example in which a receiving device according toan embodiment displays an HDR primary video and an SDR secondary videosimultaneously;

FIG. 3A is a block diagram illustrating one example of the configurationof a transmitting device according to an embodiment;

FIG. 3B is a block diagram illustrating another example of theconfiguration of a transmitting device according to an embodiment;

FIG. 4 illustrates an example in which a receiving device according toan embodiment displays a basic broadcast video, a data broadcast video,etc., simultaneously;

FIG. 5 is a block diagram illustrating another example of theconfiguration of a transmitting device according to an embodiment;

FIG. 6 is a block diagram illustrating another example of theconfiguration of a transmitting device according to an embodiment;

FIG. 7 illustrates an HDR EOTF and an SDR EOTF according to anembodiment;

FIG. 8 illustrates an example in which a receiving device according toan embodiment displays a basic broadcast caption and another videosimultaneously;

FIG. 9 is a block diagram illustrating one example of the configurationof a receiving device according to an embodiment;

FIG. 10 is a flowchart illustrating one example of operations performedby a receiving device according to an embodiment;

FIG. 11 illustrates an example of transition in an image that isdisplayed by a receiving device according to an embodiment;

FIG. 12 is a block diagram illustrating another example of theconfiguration of a receiving device according to an embodiment;

FIG. 13 is a flowchart illustrating another example of operationsperformed by a receiving device according to an embodiment;

FIG. 14A is a flowchart illustrating a transmission method according toone aspect of the present disclosure;

FIG. 14B is a block diagram illustrating the configuration of atransmitting device according to one aspect of the present disclosure;

FIG. 15A is a flowchart illustrating a reception method according to oneaspect of the present disclosure; and

FIG. 15B is a block diagram illustrating the configuration of areceiving device according to one aspect of the present disclosure.

DETAILED DESCRIPTION OF THE EMBODIMENT Underlying Knowledge FormingBasis of the Present Disclosure

In relation to NPL 1 described in the “BACKGROUND” section, theinventors have found the problem indicated below.

In NPL 1, it is presumed that graphics are created with the SDR, andwhen video on which the graphics are to be superimposed is an HDR video,the dynamic range of the graphics is converted from the SDR into theHDR, and the graphics are displayed with the HDR.

At present, SDR videos are more often provided than HDR videos as videoon which graphics are to be superimposed. Therefore, it is reasonablethat graphics created with the SDR be provided and only when video onwhich the graphics are to be superimposed is an HDR video, the dynamicrange of the graphics be converted from the SDR into the HDR.

However, as HDR videos become common, the frequency of the dynamic rangeof graphics being converted into the HDR and the graphics beingdisplayed with the HDR may become higher than the frequency of graphicsbeing displayed with the SDR. Generally, rather than converting graphicscreated with the SDR into HDR graphics and displaying the graphics withthe HDR, it is preferable that graphics created with the HDR bedisplayed with the HDR because such graphics are displayed as a creatorof the graphics intended.

Thus, there is the possibility that along with the spread of HDR videos,graphics created originally with the HDR will be provided as well in thefuture.

The inventors noticed the above possibility, took the opportunity tostart conducting in-depth research, found various problems occurring ina conventionally unexpected environment in which provision of graphicscreated with the SDR and provision of graphics created with the HDR aremixed, and found solutions for the problems, which will be described inthe embodiment below.

In order to solve such various problems, the transmission methodaccording to one aspect of the present disclosure includes: obtaining animage and image signal characteristics information indicating one of anopto-electrical transfer function (OETF) or an electro-optical transferfunction (EOTF) as image signal characteristics of the image; andtransmitting a signal including the image and the image signalcharacteristics information.

Thus, according to whether the dynamic range of an image (for example,graphics) for data broadcasting is the SDR or the HDR, a data broadcastsignal including image signal characteristics information indicating thecorresponding OETF or EOTF is transmitted through data broadcasting. Inother words, even in an environment in which provision of graphicscreated with the SDR through data broadcasting and provision of graphicscreated with the HDR through data broadcasting are mixed, thecorresponding OETF or EOTF is transmitted together with such graphicsthrough data broadcasting. Therefore, even in such an environment, areceiving device, such as a television, can display an image, such asgraphics, for data broadcasting with an appropriate dynamic range byusing the corresponding OETF or EOTF.

Furthermore, in the obtaining of the image signal characteristicsinformation, when the image is one of text or a graphic, the imagesignal characteristics information that indicates one of an offset or ascale factor for each code value included in the image, instead of theone of the OETF or the EOTF, may be obtained.

Accordingly, the receiving device can easily convert the image signalcharacteristics, such as the dynamic range, of an image for the databroadcasting by using the offset or scale factor thereof.

Furthermore, the image may be an image for data broadcasting, and thesignal may be a data broadcast signal, in the transmitting of thesignal, the data broadcast signal may be transmitted through the databroadcasting, and the transmission method may further include: obtainingvideo for basic broadcasting different from the data broadcasting;converting, when the image signal characteristics of the image for thedata broadcasting and image signal characteristics of the video for thebasic broadcasting are different, the image signal characteristics of atleast one of the image for the data broadcasting and the video for thebasic broadcasting to obtain matched image signal characteristics of theimage for the data broadcasting and the video for the basicbroadcasting; and transmitting, through the basic broadcasting, a basicbroadcast signal including the video for the basic broadcasting andimage signal characteristics information indicating the matched imagesignal characteristics. The image signal characteristics informationincluded in the data broadcast signal may indicate one of the OETF orthe EOTF as the matched image signal characteristics.

Accordingly, the image signal characteristics, i.e., OETF or EOTF, ofthe image for the data broadcasting and the video for the basicbroadcasting are unified, and the image signal characteristicsinformation indicating the unified image signal characteristics istransmitted both through basic broadcasting and through databroadcasting. Therefore, the receiving device does not need to switchthe OETF or the EOTF for each of the image for the data broadcasting andthe video for the basic broadcasting, that is, not need to switch thedisplay process, to display these image and video simultaneously. As aresult, it is possible to facilitate mounting of the receiving device.Furthermore, since the image signal characteristics informationindicating the unified image signal characteristics is transmitted boththrough basic broadcasting and through data broadcasting, there is noneed of linkage for image signal characteristics between the receptionprocess for basic broadcast and the reception process for data broadcastin the receiving device. As a result, it is possible to facilitatemounting of the receiving device.

For example, the video for the basic broadcasting may be one of aprimary video, a secondary video, or a caption corresponding to theprimary video. Furthermore, for example, the image signalcharacteristics information may indicate one of the OETF or the EOTF andat least one of a dynamic range, a color gamut, and a white point as theimage signal characteristics.

Furthermore, the reception method according to one aspect of the presentdisclosure includes: receiving a first image and first image signalcharacteristics information indicating image signal characteristics ofthe first image; receiving a second image and second image signalcharacteristics information indicating image signal characteristics ofthe second image; converting, when the first image signalcharacteristics information and the second image signal characteristicsinformation are different, the image signal characteristics of at leastone of the first image and the second image to obtain matched imagesignal characteristics of the first image and the second image; andsimultaneously displaying the first image and the second image havingthe matched image signal characteristics. For example, each of the firstimage signal characteristics information and the second image signalcharacteristics information indicates at least one of an opto-electricaltransfer function (OETF), an electro-optical transfer function (EOTF), adynamic range, a color gamut, and a white point as the image signalcharacteristics.

Accordingly, when the image signal characteristics of the first imageare SDR OETF or EOTF, for example, and the image signal characteristicsof the second image are HDR OETF or EOTF, for example, the first andsecond images having the same OETF or EOTF are displayed simultaneously.Thus, it is possible to make the first and second images moreeye-friendly.

Furthermore, the above reception method may further include: when, whilethe first image and the second image are being displayed simultaneously,only the image signal characteristics indicated in the second imagesignal characteristics information among the first image signalcharacteristics information and the second image signal characteristicsinformation that are being received switch, converting the image signalcharacteristics of the second image after the switch or stoppingconversion that is being performed on the image signal characteristicsof the second image before the switch, to obtain matched image signalcharacteristics of the first image and the second image; andsimultaneously displaying the first image and the second image havingthe matched image signal characteristics after the conversion of theimage signal characteristics of the second image is performed orstopped.

Accordingly, even when only the image signal characteristics of thesecond image switch, the image signal characteristics of the first andsecond images being displayed can remain the same before and after theswitch. Thus, the feeling of visual discomfort due to the switch can besuppressed.

Furthermore, in the receiving of the first image and the first imagesignal characteristics information, the first image and the first imagesignal characteristics information transmitted through data broadcastingmay be received, and in the receiving of the second image and the secondimage signal characteristics information, the second image and thesecond image signal characteristics information transmitted throughbasic broadcasting different from the data broadcasting may be received.

Accordingly, for example, even when the first image for the databroadcasting is displayed with the SDR and the image signalcharacteristics of the second image for the basic broadcasting displayedat the same time as the first image switch from the SDR to the HDR, thesecond image is continuously displayed with the SDR. Thus, the feelingof visual discomfort due to the switch can be suppressed.

Furthermore, in the receiving of the first image and the first imagesignal characteristics information, the first image and the first imagesignal characteristics information transmitted through communication viaa communication network may be received, and in the receiving of thesecond image and the second image signal characteristics information,the second image and the second image signal characteristics informationtransmitted through broadcasting may be received.

Accordingly, for example, even when the first image for thecommunication is displayed with the SDR and the image signalcharacteristics of the second image for broadcasting displayed at thesame time as the first image switch from the SDR to the HDR, the secondimage is continuously displayed with the SDR. Thus, the feeling ofvisual discomfort due to the switch can be suppressed.

Note that these general and specific aspects may be implemented using asystem, a method, an integrated circuit, a computer program, or acomputer-readable recording medium such as a compact disc read-onlymemory (CD-ROM), or any combination of systems, methods, integratedcircuits, computer programs, or recording media.

Hereinafter, an embodiment will be specifically described with referenceto the drawings.

Note that each embodiment described below shows a general or specificexample. The numerical values, shapes, materials, structural elements,the arrangement and connection of the structural elements, steps, theprocessing order of the steps etc. shown in the following embodiment aremere examples, and are not intended to limit the scope of the presentdisclosure. Furthermore, among the structural elements in the followingembodiment, structural elements not recited in the independent claimsindicating the broadest concepts of the present disclosure are describedas arbitrary structural elements.

Embodiment

FIG. 1 illustrates one example of the configuration of a transmittingand receiving system and one example of the screen displayed on areceiving device according to the present embodiment.

The transmitting and receiving system includes transmitting device 100which is a broadcast station and receiving device 200 which is atelevision or the like placed in a house, for example.

Transmitting device 100 transmits broadcast content to receiving device200 through broadcasting via a broadcasting network including asatellite. Furthermore, transmitting device 100 transmits communicationcontent to receiving device 200 through communication via acommunication network such as the Internet. The broadcast content andthe communication content include an image or audio. The image is video,captions, text, or graphics, for example. The broadcasting includesbasic broadcasting and data broadcasting, which are different from eachother.

Receiving device 200 receives broadcast content and communicationcontent and reproduces the broadcast content and the communicationcontent. As a result of this reproduction, receiving device 200simultaneously displays a plurality of images included in these contentson the screen of a display device such as a display.

For example, receiving device 200 displays video 1 and video 2, whichare basic broadcast primary video and secondary video, data broadcastvideo 3, data broadcast text or graphics, communication video 4, andcommunication text or graphics simultaneously. Note that the primaryvideo and the secondary video are videos displayed simultaneously in apicture-in-picture display.

Note that the image included in the content to be transmitted includesan image having luminance in a conventional standard dynamic range (SDR)and an image having luminance in a high dynamic range (HDR) which isseveral to 100 times wider than the standard dynamic range.

The present embodiment relates to a method and a device for displayingan HDR video and an SDR video simultaneously on the screen of receivingdevice 200.

FIG. 2 illustrates an example in which receiving device 200 displays anHDR primary video and an SDR secondary video simultaneously.

When transmitting device 100 according to the present embodimentsuperimposes a plurality of images different in the dynamic range, whichis one of image signal characteristics, on one another and sends out theplurality of images as a broadcast signal, transmitting device 100unifies the image signal characteristics of these images including theopto-electrical transfer function (OETF) or the electro-optical transferfunction (EOTF). Transmitting device 100 sends out the plurality ofimages superimposed on one another and image signal characteristicsinformation including the OETF/EOTF of these images. In the presentembodiment, the OETF and EOTF or the OETF or EOTF is referred to asOETF/EOTF.

This eliminates the need for receiving device 200 to switch the displayprocess according to the image signal characteristics for each screenregion to display the HDR primary video and the SDR secondary videosimultaneously, as illustrated in FIG. 2. Specifically, it is notnecessary to switch the OETF/EOTF to be applied to each image. As aresult, it is possible to facilitate mounting of receiving device 200.

In the present embodiment, the image signal characteristics and theimage signal characteristics information corresponding to an image arereferred to as video signal characteristics and video signalcharacteristics information regardless of whether or not the image isvideo. The video signal characteristics information indicatescharacteristics of an images signal (i.e., video signalcharacteristics), and the characteristics are at least one of theOETF/EOTF, the dynamic range, the color gamut, the white point, and thelike.

In the present embodiment, as long as the video signal characteristicsof each of the primary video and the secondary video are unified, eitherthe following method (1) or (2) may be performed: (1) converting thevideo signal characteristics so as to match the video signalcharacteristics of the primary video; and (2) converting the videosignal characteristics into HDR.

By configuring the settings that the video signal characteristics arefixed to one of the video signal characteristics, that is, the HDR orthe SDR, within a certain period of time such as one program, it ispossible to reduce the frequency of switching of the display process inreceiving device 200, and distortion of images due to the switch can besuppressed.

FIG. 3A is a block diagram illustrating one example of the configurationof transmitting device 100 according to the present embodiment.

Transmitting device 100 includes converters 101 and 105, synthesizer102, sender 103, and controller 104.

Controller 104 obtains primary video signal characteristics information,which is video signal characteristics information of the primary video,and secondary video signal characteristics information, which is videosignal characteristics information of the secondary video. Subsequently,in accordance with the primary video signal characteristics informationand the secondary video signal characteristics information, controller104 outputs, to converter 101, a control signal for converting the videosignal characteristics of the primary video into the video signalcharacteristics of the secondary video. Alternatively, in accordancewith the primary video signal characteristics information and thesecondary video signal characteristics information, controller 104outputs, to converter 105, a control signal for converting the videosignal characteristics of the secondary video into the video signalcharacteristics of the primary video. Alternatively, in accordance withthe primary video signal characteristics information and the secondaryvideo signal characteristics information, controller 104 outputs, toconverter 101 or 105, a control signal for converting the video signalcharacteristics of each of the primary video and the secondary videointo the HDR or the SDR.

Furthermore, controller 104 outputs, to sender 103, video signalcharacteristics information indicating the unified video signalcharacteristics of both the primary video and the secondary video, thatis, the video signal characteristics common to the primary video and thesecondary video.

Converter 101 obtains the primary video and converts the video signalcharacteristics of the primary video on the basis of the control signaloutput from controller 104. Similarly, converter 105 obtains thesecondary video and converts the video signal characteristics of thesecondary video on the basis of the control signal output fromcontroller 104.

Synthesizer 102 synthesizes (or superimposes on one another) the primaryvideo and the secondary video output from converters 101 and 104 andoutputs the synthesized primary video and secondary video to sender 103.

Sender 103 transmits, as a basic broadcast signal through broadcasting(specifically, the basic broadcasting), a signal including thesynthesized primary video and secondary video and the unified videosignal characteristics information output from controller 104. Note thatsender 103 is a transmitter.

The transmitting and receiving system according to the presentembodiment may include a transmitting device having anotherconfiguration, as illustrated in FIG. 3B, instead of transmitting device100.

FIG. 3B is a block diagram illustrating another example of theconfiguration of the transmitting device according to the presentembodiment.

Transmitting device 100A has a function the same as or similar to thatof transmitting device 100 described above and includes synthesizer 102a, sender 103, controller 104 a, and converter 105.

Controller 104 a obtains primary video signal characteristicsinformation and secondary video signal characteristics information.Subsequently, in accordance with the primary video signalcharacteristics information and the secondary video signalcharacteristics information, controller 104 outputs, to converter 105, acontrol signal for converting the video signal characteristics of thesecondary video into the video signal characteristics of the primaryvideo.

Converter 105 obtains the secondary video and converts the video signalcharacteristics of the secondary video on the basis of the controlsignal output from controller 104 a.

Synthesizer 102 a obtains the primary video, synthesizes (orsuperimposes on one another) the primary video and the secondary videooutput from converter 105, and outputs the synthesized primary video andsecondary video to sender 103.

Sender 103 transmits, as a basic broadcast signal through broadcasting(specifically, the basic broadcasting), a signal including thesynthesized primary video and secondary video and the primary videosignal characteristics information. This primary video signalcharacteristics information indicates the unified video signalcharacteristics of both the primary video and the secondary video, thatis, the video signal characteristics common to the primary video and thesecondary video.

In such transmitting devices 100 and 100A, converter 101 or 105 convertsa primary or secondary video signal from an SDR signal into an HDRsignal or from an HDR signal into an SDR signal according to the controlsignal.

FIG. 4 illustrates an example in which receiving device 200 displays abasic broadcast video, a data broadcast video, etc., simultaneously.

Receiving device 200 displays, for example, video 1 and video 2, whichare basic broadcast primary video and secondary video, data broadcastvideo 3, and data broadcast text or graphics simultaneously.

Here, there are cases where the basic broadcast primary video, the basicbroadcast secondary video, and the data broadcast image (video, text, orgraphics) are different in the video signal characteristics such as thedynamic range.

In such a case, the transmitting and receiving system according to thepresent embodiment may include a transmitting device that unifies thevideo signal characteristics by changing the video signalcharacteristics of each image other than the basic broadcast primaryvideo into the video signal characteristics of the basic broadcastprimary video, as illustrated in FIG. 5, instead of transmitting device100 or 100A. This eliminates the need for receiving device 200 to switchthe video signal characteristics information for each type ofbroadcasting, making it possible to facilitate mounting of receivingdevice 200.

FIG. 5 is a block diagram illustrating another example of theconfiguration of the transmitting device according to the presentembodiment.

Transmitting device 100B includes senders (transmitters) 111 and 116,controllers 112, 114, and 117, and converters 113, 115, and 118.

Controller 112 obtains primary video signal characteristics informationand secondary video signal characteristics information. Subsequently, inaccordance with the primary video signal characteristics information andthe secondary video signal characteristics information, controller 112outputs, to converter 113, a control signal for converting the videosignal characteristics of the secondary video into the video signalcharacteristics of the primary video.

Converter 113 obtains the secondary video and converts the video signalcharacteristics of the secondary video on the basis of the controlsignal output from controller 112.

Sender 111 obtains the primary video, the primary video signalcharacteristics information, and the secondary video output fromconverter 113, and transmits a signal including these as a basicbroadcast signal through the basic broadcasting.

Controller 114 obtains data broadcast video signal characteristicsinformation, which is video signal characteristics information of thedata broadcast video, and the primary video signal characteristicsinformation. Subsequently, in accordance with the data broadcast videosignal characteristics information and the primary video signalcharacteristics information, controller 112 outputs, to converter 115, acontrol signal for converting the video signal characteristics of thedata broadcast video into the video signal characteristics of theprimary video.

Converter 115 obtains a data broadcast video, which is video for databroadcasting, and converts the video signal characteristics of the databroadcast video on the basis of the control signal output fromcontroller 114.

Controller 117 obtains data broadcast graphic signal characteristicsinformation, which is video signal characteristics information of databroadcast text or graphics, and primary video signal characteristicsinformation. Subsequently, in accordance with the data broadcast graphicsignal characteristics information and the primary video signalcharacteristics information, controller 117 outputs, to converter 118, acontrol signal for converting the video signal characteristics of thedata broadcast text or graphics into the video signal characteristics ofthe primary video.

Converter 118 obtains data broadcast graphics, which are text orgraphics for data broadcasting, and converts the video signalcharacteristics of the data broadcast graphics on the basis of thecontrol signal output from controller 117.

Sender 116 obtains the primary video signal characteristics information,the data broadcast video output from converter 115, and the databroadcast graphics output from converter 118, and transmits a signalincluding these as a data broadcast signal through the databroadcasting.

As described above, transmitting device 100B according to the presentembodiment includes the video signal characteristics information in eachof the basic broadcast signal and the data broadcast signal. Thiseliminates the need of linkage for video signal characteristics betweenthe process of receiving the basic broadcast signal and the process ofreceiving the data broadcast signal in receiving device 200, making itpossible to facilitate mounting of receiving device 200.

In the case where receiving device 200 can always receive and processthe basic broadcast signal and the data broadcast signal in pairs,transmitting device 100B may omit the video signal characteristicsinformation included in the data broadcast signal. In this case, thetransmission method according to the present embodiment includes:obtaining an image for the data broadcasting and video for the basicbroadcasting different from the data broadcasting; converting, when theimage signal characteristics of the image for the data broadcasting andthe image signal characteristics of the video for the basic broadcastingare different, the image signal characteristics of at least one of theimage for the data broadcasting and the video for the basic broadcastingto obtain matched image signal characteristics of the image for the databroadcasting and the video for the basic broadcasting; transmitting,through the data broadcasting, a data broadcast signal including theimage for the data broadcasting; and transmitting, through the basicbroadcasting, a basic broadcast signal including the video for the basicbroadcasting and image signal characteristics information indicating thematched image signal characteristics.

The transmitting and receiving system according to the presentembodiment may include a transmitting device having anotherconfiguration, as illustrated in FIG. 6, instead of transmitting device100B.

FIG. 6 is a block diagram illustrating another example of theconfiguration of the transmitting device according to the presentembodiment.

Transmitting device 100C includes senders (transmitters) 111 and 116 a,controllers 112, 114, and 117 a, and converters 113 and 115.

Controller 117 a obtains data broadcast graphic signal characteristicsinformation, which is video signal characteristics information of databroadcast text or graphics, and primary video signal characteristicsinformation. Subsequently, in accordance with the data broadcast graphicsignal characteristics information and the primary video signalcharacteristics information, controller 117 a outputs, to sender 116 a,conversion information for converting the video signal characteristicsof the data broadcast text or graphics into the video signalcharacteristics of the primary video. The conversion information is,specifically, an offset, a scale factor, or the like.

Sender 116 a obtains the conversion information output from controller117 a, the primary video signal characteristics information, the databroadcast video output from converter 115, and the data broadcastgraphics, and transmits a signal including these as a data broadcastsignal through the data broadcasting.

In transmitting device 100C, the conversion information (such as anoffset or a scale factor) is transmitted without conversion of the videosignal characteristics of data broadcast text or graphics. This allowsreceiving device 200 to easily convert the video signal characteristics(for example, the dynamic range) of the data broadcast text or graphicsso as to match the video signal characteristics of the basic broadcastprimary video.

As described above, in the transmission method according to the presentembodiment, the image for the data broadcasting and the image signalcharacteristics information indicating one of the OETF or the EOTF asthe image signal characteristics of the image are obtained.Subsequently, the data broadcast signal including the image for the databroadcasting and the image signal characteristics information istransmitted through the data broadcasting. Here, in the obtaining of theimage signal characteristics information, when the image is one of textor graphics, the image signal characteristics information that indicatesone of an offset or a scale factor for each code value included in theimage, instead of the one of the OETF or the EOTF, may be obtained.

Furthermore, in the transmission method according to the presentembodiment, the video for the basic broadcasting different from the databroadcasting is further obtained. When the image signal characteristicsof the image for the data broadcasting and the image signalcharacteristics of the video for the basic broadcasting are different,the image signal characteristics of at least one of the image for thedata broadcasting and the video for the basic broadcasting is convertedto obtain matched image signal characteristics of the image for the databroadcasting and the video for the basic broadcasting. Next, the basicbroadcast signal including the video for the basic broadcasting andimage signal characteristics information indicating the matched imagesignal characteristics is transmitted through the basic broadcasting.Here, the image signal characteristics information included in the databroadcast signal indicates the OETF or the EOTF as the matched imagesignal characteristics.

Here, the conversion of the video signal characteristics is specificallydescribed below.

FIG. 7 illustrates an HDR EOTF and an SDR EOTF.

When each of the above-described converters converts the dynamic range,which is one of the video signal characteristics of an image, from theSDR into the HDR, the converter converts a code value of an SDR EOTFincluded in the image into a code value of an HDR EOTF. FIG. 7illustrates a conversion example of code values when the dynamic rangeis converted from the SDR having the peak luminance of 100 nit into theHDR having the peak luminance of 1,000 nit.

In the example illustrated in FIG. 7, each of the above convertersconverts the code value of an SDR EOTF into a code value of an HDR EOTFso that the luminance range (the dynamic range) of an SDR image isconverted into the luminance value of an HDR image. Each of the aboveconverters, however, may convert the code value of an SDR EOTF into acode value of an HDR EOTF so that the luminance range of an SDR image isnot converted. In this case, each of the above converters converts thecode value of the SDR EOTF so that the luminance corresponding to thecode value of an SDR EOTF before the conversion becomes the same as theluminance corresponding to the code value of an HDR EOTF after theconversion. In other words, each of the above converters converts thecode value of the SDR EOTF by horizontally projecting a point in the SDREOTF onto a curve of the HDR EOTF.

As a result of such conversion of the code value, the video signalcharacteristics of the image are converted. Furthermore, the videosignal characteristics of a plurality of images are unified by suchconversion. As a result, in receiving device 200, the EOTF/OETF (thevideo signal characteristics information) to be applied to these imagesare also unified. Consequently, there is no need for receiving device200 to switch the display process according to the image signalcharacteristics for each screen region to display the HDR primary videoand the SDR secondary video simultaneously, as illustrated in FIG. 2.Specifically, it is not necessary to switch the OETF/EOTF to be appliedto each image. As a result, it is possible to facilitate mounting ofreceiving device 200.

Here, the peak luminance for the HDR may be either an absolute value ora relative value such as a scaling factor to dynamic range SDR.Furthermore, the peak luminance may be included in auxiliary informationof a multiplexing layer for data broadcasting.

As the multiplexing layer, the MPEG-2 transport stream (TS), the MPEG-HMMT (MPEG Media Transport), or the like is used. The auxiliaryinformation is stored by a section of the TS or a descriptor in amessage of the MMT, for example. Furthermore, when the dynamic range isswitched in units of programs, the transmitting device may indicate, inprogram information such as an event information table (EIT), whether aprogram has the SDR or the HDR.

The peak luminance for the HDR in converting of the dynamic range intothe HDR may be a default value preset in receiving device 200 or may bea value obtained using the default value. For example, when datatransmitted through broadcasting, communication, or the like includesconversion information indicating, for example, the peak luminance to beused in conversion into the HDR, receiving device 200 converts thedynamic range into the HDR according to the peak luminance. When suchconversion information is not included, receiving device 200 may convertthe dynamic range into the HDR according to a default value that is settherein or a value obtained using the default value. Receiving device200 can convert the dynamic range from the HDR into the SDR likewise aswell.

As the HDR EOTF, it is possible to use a hybrid EOTF which allows thesame code value to be applied to both the HDR and the SDR. For example,when receiving device 200 superimposes image 2 having the SDR on image 1of the hybrid type having the HDR and outputs these images as SDRimages, it is possible to superimpose the images assuming that the pixelvalues of both image 1 and image 2 are in the SDR. Therefore, thetransmitting device may add, as an HDR attribute of the primary video,the secondary video, the data broadcast image, or the like, informationfor identifying whether or not such video or image is of the hybridtype.

FIG. 8 illustrates an example in which receiving device 200 displays abasic broadcast caption and another video simultaneously.

Receiving device 200 displays, for example, video 1, which is a basicbroadcast primary video, caption 1, which is a caption for the basicbroadcast primary video, data broadcast video 3, and data broadcast textor graphics simultaneously. In the present embodiment, the video for thebasic broadcasting is the primary video, the secondary video, or thecaption corresponding to the primary video.

The transmitting device (any one of transmitting devices 100 and 100A to100C described above) transmits the basic broadcast captionindependently of video such as the primary video and the secondaryvideo. Before sending the caption, the transmitting device changes thevideo signal characteristics of a caption so that these video signalcharacteristics and the video signal characteristics of the video onwhich the caption is to be superimposed are unified.

The caption is described in an extensible markup language (XML)-basedlanguage such as the timed text markup language (TTML) of the world wideweb consortium (W3C), and the color or the luminance value of thecaption is represented by RGB values. Therefore, information foridentifying whether the RGB value designated in the XML corresponds tothe OETF/EOTF for the SDR or the HDR may be added to the XML document ormay be transmitted as video signal characteristics information of thewhole caption.

The data broadcast is configured by an application such as the hypertextmarkup language (HTML). Video signal characteristics information in thedata broadcast may indicate the SDR or the HDR as the video signalcharacteristics of the whole application. Furthermore, using an HTML tagor the like, the video signal characteristics information in the databroadcast may indicate whether each of moving images, still images, andtext to be referred to by the HTML has the SDR or the HDR.

Examples of the video signal characteristics of a plurality of imagesincluding captions to be displayed simultaneously include not only thedynamic range, but also the color gamut. Especially, in ahigh-resolution image having 4K resolution or the like, it is assumedthat not only the existing BT. 709 (Recommendation ITU-R BT. 709), butalso BT. 2020 (Recommendation ITU-R BT. 2020) which enablesrepresentation of a wider color gamut than that in BT. 709 will be used.When receiving device 200 displays images different in the color gamutsimultaneously, it is necessary to change the color gamut of one of theimages into that of the other to unify the color gamut. In this case aswell, on the basis of criteria similar to those for the dynamic range(or the OETF/EOTF), the transmitting device (or receiving device 200)can determine the color gamut that is to be chosen as the unified colorgamut.

FIG. 9 is a block diagram illustrating one example of the configurationof receiving device 200 according to the present embodiment.

Receiving device 200 includes broadcast receiver 201, communicationreceiver 202, controller 203, converter 204, and display 205.

Broadcast receiver 201 receives a basic broadcast signal and outputsvideo included in the basic broadcast signal to display 205. At thistime, broadcast receiver 201 may apply, to the video, video signalcharacteristics information included in the basic broadcast signal,thereby converting the data format of the video into a format supportedby display 205. For example, broadcast receiver 201 applies the EOTF toconvert a code value included in the video into luminance. Broadcastreceiver 201 outputs such video in the converted data format to display205. Furthermore, broadcast receiver 201 outputs, as basic broadcastvideo signal characteristics information to controller 203, the videosignal characteristics information included in the basic broadcastsignal.

Communication receiver 202 receives a communication signal, outputsvideo included in the communication signal to converter 204 as acommunication video, and outputs video signal characteristicsinformation included in the communication signal to controller 203 ascommunication video signal characteristics information. Thecommunication signal is a signal transmitted through communication via acommunication network such as the Internet.

Controller 203 obtains the basic broadcast video signal characteristicsinformation and the communication video signal characteristicsinformation. Subsequently, on the basis of the basic broadcast videosignal characteristics information and the communication video signalcharacteristics information, controller 104 outputs, to converter 204, acontrol signal for converting the video signal characteristics of thecommunication video into the video signal characteristics of the basicbroadcast video.

Converter 204 obtains the communication video from communicationreceiver 202 and converts the video signal characteristics of thecommunication video on the basis of the control signal output fromcontroller 203. Furthermore, converter 204 may obtain the basicbroadcast video signal characteristics information from broadcastreceiver 201 via controller 203 and apply the basic broadcast videosignal characteristics information to the communication video having theconverted video signal characteristics. By this application, converter204 converts the data format of the communication video into a dataformat supported by display 205. For example, converter 204 applies theEOTF to convert a code value included in the communication video intoluminance. Note that “luminance” herein is not limited to the weightedsum of RGB components and may be the intensity of each of the RGBcomponents, may be the degree of brightness of light, or may be theintensity of light. Converter 204 outputs such a communication video inthe converted data format to display 205.

Display 205 is a display device and displays the basic broadcast videooutput from broadcast receiver 201 and the communication video outputfrom converter 204 simultaneously.

There are cases where even when the video signal characteristics of thebasic broadcast and the data broadcast are unified by transmittingdevice 100 described above or the like, these video signalcharacteristics do not match the video signal characteristics for thecommunication (for example, the OETF/EOTF or the dynamic range). In sucha case, receiving device 200 according to the present embodimentconverts the video signal characteristics of the communication video sothat the video signal characteristics of the communication matches thevideo signal characteristics of the broadcast, and displays thecommunication video after the conversion. Thus, it is possible to makethe communication video more eye-friendly.

Note that regarding any of these images, it is sufficient that the videosignal characteristics thereof be unified; the video signalcharacteristics of the images may be unified on the basis of the databroadcast image, the communication image, or the like.

Receiving device 200 may change the video signal characteristics (suchas brightness, hue, or contrast) of an on-screen display (OSD) such asthe channel selection information or sound volume to be displayed ondisplay 205, according to the video signal characteristics of the basicbroadcast. For example, when the dynamic range of the basic broadcastvideo is the HDR, receiving device 200 can increase the contrast of theOSD such as the channel selection information or the sound volume indisplaying the video so that the visibility thereof is improved.

FIG. 10 is a flowchart illustrating operations performed by receivingdevice 200 according to the present embodiment.

Controller 203 of receiving device 200 determines whether or not thebasic broadcast video signal characteristics information and thecommunication video signal characteristics information are the same(Step S101). Here, when controller 203 determines that these are thesame (YES in Step S101), controller 203 outputs, to converter 204, acontrol signal that does not convert the video signal characteristics ofthe communication video (Step S102). When controller 203 determines thatthose are not the same (NO in Step S101), controller 203 outputs, toconverter 204, a control signal instructing to convert the video signalcharacteristics of the communication video (Step S103).

As described above, in the reception method according to the presentembodiment, a first image and first image signal characteristicsinformation indicating the image signal characteristics of the firstimage are received. Next, a second image and second image signalcharacteristics information indicating the image signal characteristicsof the second image are received. Subsequently, when the first imagesignal characteristics information and the second image signalcharacteristics information are different, the image signalcharacteristics of at least one of the first image and the second imageis converted to obtain matched image signal characteristics of the firstimage and the second image. Furthermore, the first image and the secondimage having the matched image signal characteristics are displayedsimultaneously. Here, the first image signal characteristics informationand the second image signal characteristics information each indicate atleast one of the OETF, the EOTF, the dynamic range, the color gamut, andthe white point as image signal characteristics. Here, in the abovereception of the first image and the first image signal characteristicsinformation, the first image and the first image signal characteristicsinformation transmitted through communication via a communicationnetwork are received. In the above reception of the second image and thesecond image signal characteristics information, the second image andthe second image signal characteristics information transmitted throughbroadcasting are received. Alternatively, in the above reception of thefirst image and the first image signal characteristics information, thefirst image and the first image signal characteristics informationtransmitted through data broadcasting may be received. Likewise, in theabove reception of the second image and the second image signalcharacteristics information, the second image and the second imagesignal characteristics information transmitted through basicbroadcasting different from data broadcasting may be received.

FIG. 11 illustrates an example of transition in an image that isdisplayed by the receiving device according to the present embodiment.

For example, there are cases where, while the receiving device isdisplaying a plurality of videos simultaneously, the dynamic range ofpart of the videos switches from the SDR to the HDR or from the HDR tothe SDR or the like. As a characteristic example, it is assumed that thedynamic range of a primary video program switches while the receivingdevice is displaying a data broadcast image. At this time, if thedynamic range of the luminance of the primary video switches while thedata broadcast image is being displayed, visual discomfort would be feltdue to a difference in brightness between the video before the switchand the same video after the switch.

Thus, the transmitting and receiving system according to the presentembodiment may include receiving device 200A instead of receiving device200. In receiving device 200A, the dynamic range is fixed while the databroadcast image is being displayed.

For example, while receiving device 200A is displaying a data broadcastimage (specifically, video 3 and text, graphics, etc.) and program 1,which is a basic broadcast primary video, as illustrated in (a) of FIG.11, the primary video switches from program 1 to program 2 asillustrated in (b) of FIG. 11. Here, the dynamic range of program 1 isthe SDR, the dynamic range of program 2 is the HDR, and the dynamicrange of the data broadcast image has been the SDR since when program 1was reproduced.

Receiving device 200A according to the present embodiment displaysprogram 2, which is a primary video, with the SDR while the databroadcast image is being displayed with the SDR, as illustrated in (b)of FIG. 11, even after the primary video switches from program 1 havingthe SDR to program 2 having the HDR. Specifically, receiving device 200Aconverts the video signal characteristics of program 2 into video signalcharacteristics for the SDR and applies the SDR EOTF/OETF to program 2.Subsequently, as illustrated in (c) of FIG. 11, receiving device 200Adisplays program 2 with the HDR after the display of the data broadcastimage is ended. Specifically, receiving device 200A does not convert thevideo signal characteristics of program 2 and applies the HDR EOTF/OETFto program 2.

In this way, in the case where during display of a plurality of videos,the dynamic range of part of the videos upon reception switches,receiving device 200A according to the present embodiment determineswhether the video is to be displayed with the HDR or the SDR so that thedynamic range of the video being already displayed does not switch. Inother words, receiving device 200A controls whether or not to convertthe video signal characteristics of the video being already displayed.

Note that in order that the dynamic range of the basic broadcast primaryvideo being displayed does not switch while the data broadcast image isbeing displayed, receiving device 200A controls conversion of the videosignal characteristics of the primary video. Such control is, however,not limited to the data broadcast image and the basic broadcast primaryvideo; receiving device 200A may perform the above-described control ona plurality of any images. For example, receiving device 200A mayperform the above-described control on the communication video and thebasic broadcast video.

FIG. 12 is a block diagram illustrating another example of theconfiguration of receiving device 200A according to the presentembodiment.

Receiving device 200A includes broadcast receiver 201, communicationreceiver 202, controller 203 a, converters 204 and 206, and display 205.

Broadcast receiver 201 receives a basic broadcast signal and outputsvideo included in the basic broadcast signal to converter 206.Furthermore, broadcast receiver 201 outputs, as basic broadcast videosignal characteristics information to controller 203 a, the video signalcharacteristics information included in the basic broadcast signal.

Communication receiver 202 receives a communication signal, outputsvideo included in the communication signal to converter 204 as acommunication video, and outputs video signal characteristicsinformation included in the communication signal to controller 203 a ascommunication video signal characteristics information.

Controller 203 a obtains the basic broadcast video signalcharacteristics information and the communication video signalcharacteristics information. Subsequently, on the basis of the basicbroadcast video signal characteristics information and the communicationvideo signal characteristics information, controller 203 a outputs acontrol signal to converters 204 and 206. This control signal is forconverting both the video signal characteristics of the basic broadcastvideo and the video signal characteristics of the communication videointo the HDR or the SDR. Specifically, in the case where during displayof the basic broadcast video and the communication video, the videosignal characteristics of one of the videos switch, that is, thesevideos have different video signal characteristics, controller 203 aoutputs a control signal for converting the video signal characteristicsof the one of the videos. As a result of this conversion, the videosignal characteristics of one of the videos are the same before andafter the switch, and the video signal characteristics of both thevideos are maintained in the same state.

Note that in the case where when the video signal characteristics of oneof the above-described videos are being converted, that video signalcharacteristics switch, controller 203 a may cause converter 204 or 206to stop the conversion so that the video signal characteristics of boththe videos are maintained in the same state. Specifically, as a resultof converter 204 converting the video signal characteristics of thecommunication video from the SDR to the HDR, both the basic broadcastvideo and the communication video are displayed with the HDR. In such asituation, when the video signal characteristics of the video beingreceived by communication receiver 202 switch from the SDR to the HDR,controller 203 a causes converter 204 to stop the conversion beingperformed by converter 204. Thus, both the basic broadcast video and thecommunication video can be continuously displayed with the HDR beforeand after the switch of the video signal characteristics.

Converter 204 obtains the communication video from communicationreceiver 202 and converts the video signal characteristics of thecommunication video on the basis of the control signal output fromcontroller 203 a. Furthermore, converter 204 may obtain, from controller203 a, video signal characteristics information corresponding to theconverted video signal characteristics, and apply the video signalcharacteristics information to the communication video having theconverted video signal characteristics. By this application, converter204 converts the data format of the communication video into a dataformat supported by display 205. For example, converter 204 applies theEOTF to convert a code value included in the communication video intoluminance. Converter 204 outputs such a communication video in theconverted data format to display 205.

Converter 206 obtains the basic broadcast video from broadcast receiver201 and converts the video signal characteristics of the basic broadcastvideo on the basis of the control signal output from controller 203 a.Furthermore, converter 206 may obtain, from controller 203 a, videosignal characteristics information corresponding to the converted videosignal characteristics, and apply the video signal characteristicsinformation to the basic broadcast video having the converted videosignal characteristics. By this application, converter 206 converts thedata format of the basic broadcast video into a data format supported bydisplay 205. For example, converter 206 applies the EOTF to convert acode value included in the basic broadcast video into luminance.Converter 206 outputs such a basic broadcast video in the converted dataformat to display 205.

Display 205 is a display device and simultaneously displays the basicbroadcast video output from converter 206 and the communication videooutput from converter 204.

FIG. 13 is a flowchart illustrating operations performed by receivingdevice 200A according to the present embodiment.

First, controller 203 a of receiving device 200A determines whether ornot the video signal characteristics of any of the plurality of videosbeing displayed have switched (Step S100). Here, when the video signalcharacteristics are determined to have switched (YES in Step S100),controller 203 a outputs, to converter 204 or 206, a control signalinstructing to convert or not to convert the video signalcharacteristics so that the video signal characteristics are the samebefore and after the switch.

When the video signal characteristics are determined to have notswitched (NO in Step S100), controller 203 a determines whether or notthe basic broadcast video signal characteristics information and thecommunication video signal characteristics information are the same(Step S101). Here, when controller 203 a determines that these are thesame (YES in Step S101), controller 203 a outputs, to converters 204 and206, a control signal that does not convert the video signalcharacteristics (Step S102). When controller 203 a determines that thoseare not the same (NO in Step S101), controller 203 a outputs, toconverter 204 and converter 206, a control signal instructing to convertthe video signal characteristics of at least one of the basic broadcastvideo and the communication video (Step S103).

As described above, in the reception method according to the presentembodiment, when, while the first image and the second image are beingdisplayed simultaneously, only the image signal characteristicsindicated in the second image signal characteristics information amongthe first image signal characteristics information and the second imagesignal characteristics information that are being received switch, theimage signal characteristics of the second image after the switch isconverted, or conversion that is being performed on the image signalcharacteristics of the second image before the switch is stopped, toobtain matched image signal characteristics of the first image and thesecond image. The first image and the second image having the matchedimage signal characteristics are displayed simultaneously after theconversion of the image signal characteristics of the second image isperformed or stopped.

Accordingly, even when only the image signal characteristics of thesecond image switch, the image signal characteristics of the first andsecond images being displayed can remain the same before and after theswitch. Thus, the feeling of visual discomfort due to the switch can besuppressed.

SUMMARY

FIG. 14A is a flowchart illustrating a transmission method according toone aspect of the present disclosure.

The transmission method according to one aspect of the presentdisclosure includes Step S11 and Step S12. In Step S11, an image for thedata broadcasting and image signal characteristics informationindicating the OETF or the EOTF as the image signal characteristics ofthe image are obtained. In Step S12, a data broadcast signal includingthe image for the data broadcasting and the image signal characteristicsinformation is transmitted through the data broadcasting.

FIG. 14B is a block diagram illustrating the configuration of atransmitting device according to one aspect of the present disclosure.

Transmitting device 10 according to one aspect of the present disclosureincludes obtainer 11 and transmitter 12. Obtainer 11 obtains an imagefor the data broadcasting and image signal characteristics informationindicating the OETF or the EOTF as the image signal characteristics ofthe image. Transmitter 12 transmits a data broadcast signal includingthe image for the data broadcasting and the image signal characteristicsinformation through the data broadcasting.

Thus, according to whether the dynamic range of an image (for example,graphics) for the data broadcasting is the SDR or the HDR, a databroadcast signal including image signal characteristics informationindicating the corresponding OETF or EOTF is transmitted through thedata broadcasting. In other words, even in an environment in whichprovision of graphics created with the SDR through the data broadcastingand provision of graphics created with the HDR through the databroadcasting are mixed, the corresponding OETF or EOTF is transmittedtogether with such graphics through the data broadcasting. Therefore,even in such an environment, a receiving device, such as a television,can display an image, such as graphics, for data broadcasting with anappropriate dynamic range by using the corresponding OETF or EOTF.

FIG. 15A is a flowchart illustrating a reception method according to oneaspect of the present disclosure.

The reception method according to one aspect of the present disclosureincludes Steps S21 to S24.

In Step S21, a first image and first image signal characteristicsinformation indicating the image signal characteristics of the firstimage are received. In Step S22, a second image and second image signalcharacteristics information indicating the image signal characteristicsof the second image are received. In Step S23, when the first imagesignal characteristics information and the second image signalcharacteristics information are different, the image signalcharacteristics of at least one of the first image and the second imageis converted to obtain matched image signal characteristics of the firstimage and the second image. In Step S24, the first image and the secondimage having the matched image signal characteristics are displayedsimultaneously.

FIG. 15B is a block diagram illustrating the configuration of areceiving device according to one aspect of the present disclosure.

Receiving device 20 according to one aspect of the present disclosureincludes first receiver 21, second receiver 22, converter 23, anddisplay 24.

First receiver 21 receives a first image and first image signalcharacteristics information indicating the image signal characteristicsof the first image. Second receiver 22 receives a second image andsecond image signal characteristics information indicating the imagesignal characteristics of the second image. When the first image signalcharacteristics information and the second image signal characteristicsinformation are different, converter 23 converts the image signalcharacteristics of at least one of the first image and the second imageto obtain matched image signal characteristics of the first image andthe image signal characteristics of the second image. Display 24simultaneously displays the first image and the second image having thematched image signal characteristics.

Accordingly, when the image signal characteristics of the first imageare SDR OETF or EOTF, for example, and the image signal characteristicsof the second image are HDR OETF or EOTF, for example, the first andsecond images having the same OETF or EOTF are displayed simultaneously.Thus, it is possible to make the first and second images moreeye-friendly.

Note that in the embodiment described above, each of the structuralelements may be configured in the form of an exclusive hardware productor may be realized by executing a software program suitable for each ofthe structural elements. Each of the structural elements may be realizedby means of a program executing unit, such as a central processing unit(CPU) and a processor, reading and executing the software programrecorded on a recording medium such as a hard disk or a semiconductormemory. Here, software for implementing the transmitting device or thereceiving device according to the above embodiment is a program whichcauses a computer to execute the steps included in the flowchartillustrated in FIG. 10, FIG. 13, FIG. 14A, or FIG. 15A.

Although the transmitting device and the receiving device according toone or more aspects are described thus far based on the embodiment, thepresent disclosure is not limited to this embodiment. Variousmodifications of the present embodiment as well as embodiments resultingfrom combinations of structural elements of the different embodimentsthat may be conceived by those skilled in the art may be included withinthe scope of one or more aspects as long as these do not depart from theessence of the present disclosure.

INDUSTRIAL APPLICABILITY

The present disclosure produces the advantageous effect of displaying animage appropriately and can be used, for example, as a transmittingdevice which transmits images such as a television video, a caption,text, or graphics through broadcasting or communication and a receivingdevice, such as a television, which receives and displays such images.

What is claimed is:
 1. A transmission method, comprising: obtaining animage and image signal characteristics information indicating one of anopto-electrical transfer function (OETF) or an electro-optical transferfunction (EOTF) as image signal characteristics of the image; andtransmitting a signal including the image and the image signalcharacteristics information.
 2. The transmission method according toclaim 1, wherein in the obtaining of the image signal characteristicsinformation, when the image is one of text or a graphic, the imagesignal characteristics information that indicates one of an offset or ascale factor for each code value included in the image, instead of theone of the OETF or the EOTF, is obtained.
 3. The transmission methodaccording to claim 1, wherein the image is an image for databroadcasting, and the signal is a data broadcast signal, in thetransmitting of the signal, the data broadcast signal is transmittedthrough the data broadcasting, the transmission method furthercomprises: obtaining video for basic broadcasting different from thedata broadcasting; converting, when the image signal characteristics ofthe image for the data broadcasting and image signal characteristics ofthe video for the basic broadcasting are different, the image signalcharacteristics of at least one of the image for the data broadcastingand the video for the basic broadcasting to obtain matched image signalcharacteristics of the image for the data broadcasting and the video forthe basic broadcasting; and transmitting, through the basicbroadcasting, a basic broadcast signal including the video for the basicbroadcasting and image signal characteristics information indicating thematched image signal characteristics, and the image signalcharacteristics information included in the data broadcast signalindicates one of the OETF or the EOTF as the matched image signalcharacteristics.
 4. The transmission method according to claim 3,wherein the video for the basic broadcasting is one of a primary video,a secondary video, or a caption corresponding to the primary video. 5.The transmission method according to claim 1, wherein the image signalcharacteristics information indicates one of the OETF or the EOTF and atleast one of a dynamic range, a color gamut, and a white point as theimage signal characteristics.
 6. A reception method, comprising:receiving a first image and first image signal characteristicsinformation indicating image signal characteristics of the first image;receiving a second image and second image signal characteristicsinformation indicating image signal characteristics of the second image;converting, when the first image signal characteristics information andthe second image signal characteristics information are different, theimage signal characteristics of at least one of the first image and thesecond image to obtain matched image signal characteristics of the firstimage and the second image; and simultaneously displaying the firstimage and the second image having the matched image signalcharacteristics, wherein the first image signal characteristicsinformation indicates one of an opto-electrical transfer function (OETF)or an electro-optical transfer function (EOTF) as the image signalcharacteristics of an image corresponding to one of a first dynamicrange or a second dynamic range that is wider than the first dynamicrange, and the second image signal characteristics information indicatesone of the OETF or EOTF as the image signal characteristics of an imagecorresponding to the other of the first dynamic range and the seconddynamic range.
 7. The reception method according to claim 6, whereineach of the first image signal characteristics information and thesecond image signal characteristics information indicates at least oneof an opto-electrical transfer function (OETF), an electro-opticaltransfer function (EOTF), a dynamic range, a color gamut, and a whitepoint as the image signal characteristics.
 8. The reception methodaccording to claim 6, further comprising: when, while the first imageand the second image are being displayed simultaneously, only the imagesignal characteristics indicated in the second image signalcharacteristics information among the first image signal characteristicsinformation and the second image signal characteristics information thatare being received switch, converting the image signal characteristicsof the second image after the switch or stopping conversion that isbeing performed on the image signal characteristics of the second imagebefore the switch, to obtain matched image signal characteristics of thefirst image and the second image; and simultaneously displaying thefirst image and the second image having the matched image signalcharacteristics after the conversion of the image signal characteristicsof the second image is performed or stopped.
 9. The reception methodaccording to claim 6, wherein in the receiving of the first image andthe first image signal characteristics information, the first image andthe first image signal characteristics information transmitted throughdata broadcasting are received, and in the receiving of the second imageand the second image signal characteristics information, the secondimage and the second image signal characteristics informationtransmitted through basic broadcasting different from the databroadcasting are received.
 10. The reception method according to claim6, wherein in the receiving of the first image and the first imagesignal characteristics information, the first image and the first imagesignal characteristics information transmitted through communication viaa communication network are received, and in the receiving of the secondimage and the second image signal characteristics information, thesecond image and the second image signal characteristics informationtransmitted through broadcasting are received.
 11. A transmittingdevice, comprising: an obtainer which obtains an image and image signalcharacteristics information indicating one of an opto-electricaltransfer function (OETF) or an electro-optical transfer function (EOTF)as image signal characteristics of the image; and a transmitter whichtransmits a signal including the image and the image signalcharacteristics information.
 12. A receiving device, comprising: a firstreceiver which receives a first image and first image signalcharacteristics information indicating image signal characteristics ofthe first image; a second receiver which receives a second image andsecond image signal characteristics information indicating image signalcharacteristics of the second image; a converter which, when the firstimage signal characteristics information and the second image signalcharacteristics information are different, converts the image signalcharacteristics of at least one of the first image and the second imageto obtain matched image signal characteristics of the first image andthe second image; and a display which simultaneously displays the firstimage and the second image having the matched image signalcharacteristics.